Mixtures of zirconyl salts and trialkoxysilylpropylamines as coupling agents

ABSTRACT

The bond strength between solid inorganic materials, such as glass, and certain organic resins, such as epoxies, is strengthened by treatment of the solid with a mixture of a water soluble zirconyl salt and a gamma-trialkoxysilylpropylamine prior to the formation of the bond.

United States Fatent Inventor Edwin F. Plueddemann c/o Dow CorningCorp., Midland, Mich. 48460 App1.No1 848,731

Filed Aug. 8, 1969 Patented Dec. 14, 1971 MIXTURES 0F ZIRCONYL SALTS ANDTRlALKOXYSILYLPROPYLAMINES AS COUPLING AGENTS 7 Claims, No Drawings US.Cl 117/72, l17/76T, 117/126GN, 117/126 GF, 117/121, 260/4293, 117/126 GElnt. Cl ..C03c 25/02, B32b 17/04 Field of Search PrimaryExaminer-William D. Martin Assistant ExaminerDavid Cohen An0rneys-RobertF. Fleming, .lr., Laurence R. Hobey, Harry D. Dingman and Norman E.Lewis ABSTRACT: The bond strength between solid inorganic materials,such as glass, and certain organic resins, such as epoxies, isstrengthened by treatment of the solid with a mixture of a water solublezirconyl salt and a gamma-trialkoxysilylpropylamine prior to theformation of the bond.

MEXTURES F ZIRCONYL SALTS AND TRXALKOXYSTLYLPROPYLAMINES AS COUPLINGAGENTS This invention relates to the treatment of solid inorganicmaterials in order to obtain superior bonding of these materials toorganic resins. In one aspect, the invention relates to the treatment offibrous glass which is combined with resinous material to formhigh-strength composites. In another aspect, the invention relates to asingle treatment which enhances the handling properties of glass fiberswhile at the same time improving the physical properties of compositesfabricated from the treated glass and organic resins.

There are a number of products in which an organic resin is bonded to aninorganic solid. Such bonding is an integral step in the production ofmany structural materials, glass-reinforced plastics, laminates and thelike. The strength of the bond between the solid reinforcement orsubstrate and the resin is often determinative of the ultimate strengthof the article. The strength of this bond is influenced by severalfactors, including wettability of the solid surface by the resin and thepresence of chemical bonding between the surface and the resin. In thefabrication of these bonded products, ease in handling the reinforcingsolid is especially desirable. To obtain ease in handling of glassfibers, these materials are often coated with an antistatic agent, suchas a transition metal salt. Examples of these metal salts as used insizing compositions are given in British Pat. 1,138,528.

it has been found that the combination of certain of these transitionmetal salts with amino-functional silanes provides superior bondstrengths in the reinforcement of certain organic resins.

Accordingly, it is an object of the invention to provide a method ofenhancing the strength of reinforced plastic articles.

It is another object of the invention to provide, coated glass fiberswhich exhibit an improved receptivity to organic resins.

A further object of the invention is to provide, as article ofmanufacture, a high strength composite article of reinforced resinousmaterials.

These and other objects of the invention will be apparent to one skilledin the art upon consideration of the following specification andappended claims.

The invention provides a method of improving the receptivity of solidinorganic materials for organic resins which comprises contacting thesolid with an aqueous solution containing from 0.l to 5 weight percentofa mixture consisting essentially of l to molar parts ofa water-solublezirconyl salt and l to 10 molar parts ofa water-solublegamma-tri-alkoxysilylpropylamine.

The treated solid material is used to reinforce organic resins which arecapable of reacting with the amine functionality of the coating.Illustrative of such resins are know commercial phenolic resins, bothresols and novalac; amino resins, which are the reaction products ofurea or melamine with formaldehyde, polyamides which are the reactionproducts of dianhydrides with diamines; such as poly(hexamethylene,diamide, adipate), poly(benzedene, fumarate), and poly(3-aminopropionicacid); epoxy resins, such as condensation products of epichlorohydrinand bis-(para-hydroxyphenol)-dimethylmethane;urethane resins, includingthe adducts of organopolyisocyanates and polyhydric alcohols such as theadduct of paraphenylene diisocyanate and polyethylene gylcol;polyesters, including the gylcerol-phthalate resins, theglycerol-maleate resins and glycerol-terephthalate resins, as well ascorresponding alcohol-, acidand oil-modified products, and alkyd resins,which are the reaction products of a saturated polybasic acid and apolyol.

Composite articles of manufacture, in which these resins are bonded tosolid surface which have been treated with the solution of zirconyl saltand amine-functional trialkoxysilane, exhibit superior strength whencompared to articles in which the solid surface has been treated withother metal salts and the same silane.

Water-soluble zirconyl salts, suitable for practice of the invention,include ammonium zirconyl carbonate, zirconium acetate, basic zirconylchloride, zirconium oxychloride, and zirconyl nitrate.

Any water-soluble gamma-trialkoxysilylpropylamine can be used in thepractice of the invention. These amines include (CH (CH O) SiCl-l CH CHN(Cl-l (C H O) SiCH CH CH NHCH CH NH (CH O) SiCH CH Cl-l N(CH Theseamine-functional silanes a re well known in tl art. Thetrimethoxysilanes are preferred because of their ready commercialavailability.

The components of the coupling agent are mixed in water and form stableaqueous solution. The acidic zirconyl salts may require the addition ofacid in an amount equivalent to the amine in order to obtain a stablesolution. The exact nature of the aqueous solution is not known, but itis apparent from testing that the zirconyl salt-amine mixture provides amore polar surface than amino-functional silane alone does. This resultsin improved wettability of that surface by organic resins which isdirectly related to enhanced physical strength obtained in the compositeformed from the treated solids.

Any solid inorganic material can be used in this application, forexample, glass cloth or fiber, powdered glass, rock silicas, or clay.Sheets of glass and silicone resins are also useful. Metals which can beused are aluminum, copper, silver, steel, iron, nickel and the like.These metals can be used in the form of sheeting, wire, rod, filings orpowder. Solid material in the form of metal oxides such as powderedaluminum, iron oxide or titanium dioxide are also suitable asreinforcing solids.

The zirconyl saltamine solution can be applied to the surface of thesolid by any suitable method such as dipping, spraying, or brushing. Aspreviously discussed it is preferred to apply the solution in a diluteform from 0.1 to 5 weight percent. This is more in the nature ofeconomic preference since higher concentrations of the materials insolution are operable but give no further enhancement of bond strengths.Treatment of glass fibers in accordance with the invention not onlyenhances bond strength but improves the handling characteristics of thefiber. Thus the fibers are more easily chopped and the weaving of thematerial onto glass cloth is facilitated. Other conventional treatingmaterials, such as sizing agents and lubricants, can be utilized inconjunction with the desired solution.

The thermoplastic organic resins, such as polyamide, are bonded to thetreated solid by heating the polymer to above its softening temperatureand contacting the reinforcing solid. The bond with thermosettingpolymers, for example epoxy resins, is efiected by mixing the liquidresin and treated material thereafter curing the composite. Thecomposite article thus formed consists of the solid inorganic materialhaving its surface treated with the defined mixture of zirconyl saltsand gamma-trialkoxysilylpropylamine which is bonded to organic resin,the composite article can take a variety of forms. A single piece of thesolid material can be bonded with the resin to form a continuous twodimensional bond. A laminate of alternating sheets of the reinforcingmaterial and resin can also be made, or granules or fibers of the solidcan be dispersed throughout a resin.

The following examples are illustrative only, and should not beconstrued as limiting the invention, which is properly delineated in theappended claims.

EXAMPLE l Equimolar mixtures of various transition metal salts with thesame amino functional trialkoxysilane were dissolved in acidified waterto give an aqueous solution containing a 5 percent solids. Films ofthese solutions were coated onto clean aluminum panels and dried at for15 minutes. The primed aluminum panels were then coated with acommercially available 2-part urethane paint. The painted panels wereand immediately testing for flexural strength.

Properties of the various laminates are given below:

EPOXY-GLASS CLOTH LAMINATES Flexural strength (p.s.i.

Total conceu- X10 boiling water at.

tration of treating agent, 2 48 72 Treatment on glass percent Dry hrshrs. hrs.

(CIiIaOhSi CH2 IlNH CH2) :NH:

p usmamzronrcona 0. 5 73. 4 72.1 66.1 ZrOOHCl O. 5 78. 6 72. 4 45. 8ZrO(NO 0. 5 78.0 69. 7 44. 4 ZIOC]: 0. 5 7.77 78. 3 60.6 2ZrO2(C2HaO2)z0. 6 79. 9 74. 3 57. 4 HzZI'0z(CzH3O2)2 0.1 80.0 72.6 51.4 0.1 84. 80. 661. 8 0. 58. 0 55. 0

Primed Aluminum Panels Transition metal salts with (Cl-1,0 ),SiCH,CH,CH,

Time to Form Pain! Blisters (minutes) NHCH,CH=NH,

Paint did not adhere to these prime panels. Applied from unacidificdsolution.

These metal salts are representative of the material available in theprior art, it will be noted that only the combination of zironium saltswith the silane coupling agent impart equal or improved adhesion andwater resistance.

EXAMPLE 2 An equimolar mixture of the silane utilized in the example 1and (NH ZrOH(CO was added to water to form a 0.5 weight percent aqueoussolution. Various other mixtures of zirconyl salts and the silane inacidified water were used to form treating solution. For purposes ofcomparisons, a mi ture of equimolar amounts of chromium chloride and thesilane was added to water to form a 0.5 percent treating solution. Thedifferent solutions were used to treat samples of heat cleaned E-glass.type 18], glass cloth. After immersion in a solution. the glass clothwas air dried for 30 minutes at room temperature and then heated 7minutes at l 10C. Portions of the treated glass cloth were laminatedwith an aromatic amine-cured epoxy resin. The treated cloth wasimpregnated with the organic resin and the impregnated cloth was thenstacked into a l4-ply laminate. The epoxy resin employed was acommercial material consisting of a condensation product of two moles ofepichlorohydrin and one mol of bis(parahydroxylphenyl)dimethylmethane.This polymer had an epoxide equivalent weight of 187 to I93. Thecatalyst employed was metaphenylenediamine. which was used in amount 13percent by weight based on the weight of the epoxy resin.

The epoxy resin laminates were cured in a press for 30 minutes at 150 C.The flexural strength ofcured product was determined (dry strength). Thesamples of the laminates were then immersed in boiling water and testedfor flexural strength after 2. 48 and 72 hours in the boiling water. Thetest procedures involved quenching samples in cold water, drying Thisdata demonstrates the enhanced laminates strength obtained when theglass cloth is treated with a combination of the zirconyl salts andgamma-trialkoxysilylpropylamine.

EXAMPLE 3 Certain of the 0.5 percent solutions in Example 2 were used totreat additional glass samples. These glass samples were laminated witha commercially available phenolic resin. Laminates were prepared in thesame manner as described above and cured under the same conditions.These phenolic resin-treated glass laminates were compared with alaminate formed from untreated glass and the same phenolic resin. Thetable below relates the strength obtained to the various glasstreatments utilized.

Phenolic Glass Cloth Laminates Treatment on Glass .Flexural Strength(psi. X 10) practice of the invention. it will be noted that theuntreated glass results in a very great loss in strength after 48 hoursin boiling water. while the treated glass laminates exhibit aconsiderable retention of this wet strength.

Reasonable modification and variation are within the scope of theinvention which sets forth an improved method for increasing thestrengths of a reinforced organic resin composite.

That which is claimed is:

l. A method ofimproving the bond strength between a solid inorganicmaterial and an organic resin which is capable of reacting with aminoradicals. said method comprising the steps of( l contacting theinorganic material. prior to bonding, with an aqueous solutionconsisting essentially of from 0.] to 5 weight percent of a mixture of lto ID molar parts of a water-soluble zirconyl salt and l to 10 molarparts of a watersoluble gamrna-trialkoxysilylpropylamine; (2 drying thetreated inorganic material; and (3 bonding said organic resin to thetreated inorganic material.

2. The method of claim 1 wherein the solid inorganic material is fibrousglass.

3. The method of claim 1 wherein the amine is of the formul8 a)a 'lzi a2 2 2- 4. The method of claim 1 wherein the zirconyl salt is 2 2( 2 32)2' 5. The method of claim 1 wherein the zirconyl salt is L).1 3 )3- 6.The method of claim 1 wherein the zirconyl salt is ZrO(OH)Cl.

7. The method of claim 1 wherein the solid is fibrous glass, the organicresin is an epoxy resin and the amine is of the formula (CH OhSi {-CH fNH-Cl-l cl-l Nl-l a rway

2. The method of claim 1 wherein the solid inorganic material is fibrousglass.
 3. The method of claim 1 wherein the amine is of the formula(CH3O3Si CH2 3NH-CH2CH2NH2.
 4. The method of claim 1 wherein thezirconyl salt is H2ZrO2(C2H3O2)2.
 5. The method of claim 1 wherein thezirconyl salt is (NH4)3ZrOH(CO3)3.
 6. The method of claim 1 wherein thezirconyl salt is ZrO(OH)Cl.
 7. The method of claim 1 wherein the solidis fibrous glass, the organic resin is an epoxy resin and the amine isof the fOrmula (CH3O)3Si CH2 3NH-CH2CH2NH2.